3/10/2012 5:00 AM PST

One of Courtney Love's ex-assistant's is shopping a new book -- claiming to offer up the singer's deepest darkest secrets ... involving her derailed love life, and rampant denial of serious drug problems.

The book -- tentatively entitled "Get Me a Xanax" -- is being shopped around to major literary agents in New York by a woman named Jessica Labrie, who worked for Love from 2010-2011.

According to the proposal -- obtained by TMZ -- "This is an unprecedented glimpse into the daily life of the chaotic widow of Kurt Cobain, by an innocuous girl who had the extraordinary chance to witness it all."

Labrie makes many allegations in her proposal -- including how Love torpedoed several romantic relationships with her obsessive behavior, and still abuses cocaine and prescription drugs like Adderall and Xanax ... despite telling people she's been "clean and sober" for years.

So far, no word on whether the book's been picked up.

Courtney tells TMZ, she hasn't taken Adderall since November 2010 -- and is adamant she never took cocaine when Labrie worked for her, adding, "I hate cocaine."